1. Field of the Invention
The present invention relates to a linear compressor and, more particularly, to a linear compressor having a zinc die-cast frame.
2. Description of the Related Art
Generally, a linear compressor is an apparatus to compress operating fluid, such as refrigerant, in a cylinder while reciprocating a piston in the cylinder using a reciprocating driving force of a linear motor.
FIG. 1 is a sectional view of a conventional linear compressor.
As shown in FIG. 1, the conventional linear compressor includes a hermetic container 2 to and from which operating fluid is introduced and discharged, and a compression unit mounted in the hermetic container 2 and adapted to compress the operating fluid.
The hermetic container 2 is provided with a fluid suction pipe 4 to introduce the operating fluid into a cylinder 10 of the compression unit, and a fluid discharge pipe 6 to discharge the operating fluid, compressed in the cylinder 10, to the outside of the hermetic container 2.
The compression unit includes the cylinder 10 configured to receive the operating fluid from the fluid suction pipe 4 provided at the hermetic container 2, a piston 20 mounted to be linearly reciprocated in the cylinder 10 to thereby compress the operating fluid in the cylinder 10, and a linear motor 30 to reciprocate the piston 20.
To the cylinder 10 is coupled a discharge unit 12 including a discharge valve 12′. The discharge unit 12 serves to discharge the compressed operating fluid from the cylinder 10 into the fluid discharge pipe 6.
The piston 20 is internally formed with a fluid passage 20′ to pass the operating fluid introduced from the fluid suction pipe 4 therethrough. A suction valve 22 is coupled to the piston 20 to introduce the operating fluid of the fluid passage 20′ into the cylinder 10.
The linear motor 30 is generally divided into a stator 32, and a mover 34 connected to the piston 20 and adapted to be reciprocated via electromagnetic interaction with the stator 32.
Meanwhile, the hermetic container 2 is internally provided with a frame 40 to support the cylinder 10 and the linear motor 30, a linear motor cover 42, and a plurality of dampers 44, 45, 46, and 47 to elastically support the frame 40 and the linear motor cover 42.
Conventionally, the frame 40 is integrally die cast with the cylinder 10 using paramagnetic aluminum.
The die-cast frame 40 and cylinder 10 have a low forming accuracy due to the nature of aluminum. For this reason, after die casting, the frame 40 and the cylinder 10 are machined, i.e. are lathed, on at least several locations a to i shown in FIG. 2 in a state wherein they are caught by a chuck.
In this case, specific parts of both the frame 40 and the cylinder 10, caught by the chuck, cannot be machined. In order to machine the overall parts of the die-cast frame 40 and cylinder 10, therefore, the frame 40 and the cylinder 10 must be machined at least two times.
Alternatively, one might propose that the frame 40 be independently die cast using aluminum and, then, be integrally coupled to the cylinder 10. However, even in the case of the independently die-cast frame 40, it must be machined on at several locations a to e shown in FIG. 3.
Now, the operation of the conventional linear compressor configured as stated above will be explained in detail.
If the linear motor 30 is driven, the piston 20 is reciprocated in the cylinder 10 using a driving force of the linear motor 30. Then, the discharge valve 12′ and the suction valve 22 are repeatedly opened or closed as they cooperate with the reciprocating piston 20.
Thereby, the operating fluid is introduced into the cylinder 10 through the fluid suction pipe 4 and the fluid passage 20′ in succession, thereby being compressed in the cylinder 10 by the piston 20 into a high-pressure fluid. Finally, the high-pressure operating fluid, compressed in the cylinder 10, is discharged out of the hermetic container 2 through the discharge unit 12 and the fluid discharge pipe 6 in succession.
The introduction, compression, and discharge of the operating fluid as stated above are continuously repeated in that order so long as the linear motor 30 is driven.
However, the conventional linear compressor as stated above has a problem in that the electromagnetic force of the linear motor 30 may be leaked through the frame 40 because the frame 40, used to support the linear motor 30, is made of aluminum. This leakage of the electromagnetic force results in a deterioration in the efficiency of the linear motor 30.
Also, since the die-cast frame 40 and cylinder 10 must be machined on a plurality of locations, they are disadvantageous in view of productivity and manufacturing costs.